NAME

Catalyst::Manual::Tutorial::AdvancedCRUD::FormFu - Catalyst Tutorial - Part 9: Advanced CRUD - FormFu

NOTE: This part of the tutorial is in progress and will be ready soon.

OVERVIEW

This is Part 9 of 10 for the Catalyst tutorial.

DESCRIPTION

This portion of the tutorial explores HTML::FormFu and how it can be used to manage forms, perform validation of form input, as well as save and restore data to/from the database.

See Catalyst::Manual::Tutorial::AdvancedCRUD for additional form management options other than HTML::FormFu.

Install `HTML::FormFu`

If you are following along in Ubuntu, it turns out that HTML::FormFu is not yet available as a package at the time this was written. To install it with a combination of apt-get packages and traditional CPAN modules, first use apt-get to install most of the modules required by HTML::FormFu:

    sudo apt-get install libtest-nowarnings-perl libdatetime-format-builder-perl \
    libdatetime-format-strptime-perl libdatetime-locale-perl \
    libhtml-tokeparser-simple-perl liblist-moreutils-perl \
    libregexp-copy-perl libregexp-common-perl libyaml-syck-perl libparams-util-perl

Then use the following command to install directly from CPAN the modules that aren't available as Ubuntu/Debian packages via apt-get:

    sudo cpan File::ShareDir Task::Weaken Config::Any HTML::FormFu \
    Catalyst::Controller::HTML::FormFu

`HTML::FormFu` FORM CREATION

This section looks at how HTML::FormFu can be used to add additional functionality to the manually created form from Part 4.

Inherit From `Catalyst::Controller::HTML::FormFu`

First, change your lib/MyApp/Controller/Books.pm to inherit from Catalyst::Controller::HTML::FormFu by changing the use base line from the default of:

    use base 'Catalyst::Controller';

to use the FormFu base controller class:

    use base 'Catalyst::Controller::HTML::FormFu';

Add Action to Display and Save the Form

Open lib/MyApp/Controller/Books.pm in your editor and add the following method:

    =head2 formfu_create
    
    Use HTML::FormFu to create a new book
    
    =cut
    
    sub formfu_create :Local :FormConfig {
        my ($self, $c) = @_;
    
        # Get the form that the :FormConfig attribute saved in the stash
        my $form = $c->stash->{form};
  
        # Check if the form as been submitted (vs. displaying the initial
        # form) and if the data based validation.  "submitted_and_valid"
        # is shorthand for "$form->submitted && !$form->has_errors"
        if ($form->submitted_and_valid) {
            # Create a new book
            my $book = $c->model('DB::Books')->new_result({});
            # Save the form data for the book
            $form->save_to_model($book);
            # Set a status message for the user
            $c->flash->{status_msg} = 'Book created';
            # Return to the books list
            $c->response->redirect($c->uri_for('list')); 
            $c->detach;
        } else {
            # Get the authors from the DB
            my @authorObjs = $c->model("DB::Authors")->all();
            # Create an array of arrayrefs where each arrayref is an author
            my @authors;
            foreach (sort {$a->last_name cmp $b->last_name} @authorObjs) {
                push(@authors, [$_->id, $_->last_name]);
            }
            # Get the select added by the config file
            my $select = $form->get_element({type => 'Select'});
            # Add the authors to it
            $select->options(\@authors);
        }
        
        # Set the template
        $c->stash->{template} = 'books/formfu_create.tt2';
    }

Create a Form Config File

Although HTML::FormFu supports any configuration file handled by Config::Any, most people tend to use YAML. First create a directory to hold your form configuration files:

    mkdir -p root/forms/books

Then create the file root/forms/books/formfu_create.yml and enter the following text:

    ---
    # indicator is the field that is used to test for form submission
    indicator: submit
    # Start listing the form elements
    elements:
        # The first element will be a text field for the title
        - type: Text
          name: title
          label: Title
          # This is an optional 'mouse over' title pop-up
          attributes:
            title: Enter a book title here
    
        # Another text field for the numeric rating
        - type: Text
          name: rating
          label: Rating
          attributes:
            title: Enter a rating between 1 and 5 here
    
        # Add a drop-down list for the author selection.  Note that we will
        # dynamically fill in all the authors from the controller but we
        # could manually set items in the drop-list by adding this YAML code:
        # options:
        #   - [ '1', 'Bastien' ]
        #   - [ '2', 'Nasseh'  ]
        - type: Select
          name: authors
          label: Author
    
        # The submit button
        - type: Submit
          name: submit
          value: Submit

NOTE: Copying and pasting YAML from perl documentation is sometimes tricky. See the "Copy-Paste versions of the YAML Config" section of this document for a foolproof procedure.

Update the CSS

Edit root/src/ttsite.css and add the following lines to the bottom of the file:

    input {
        display: block;
    }
    select {
        display: block;
    }
    .submit {
        padding-top: .5em;
        display: block;
    }

These changes will display form elements vertically. Note that the existing definition of the .error class is pulling the color scheme settings from the root/lib/config/col file that was created by the TTSite helper. This allows control over the CSS color settings from a single location.

Create a Template Page To Display The Form

Open root/src/books/formfu_create.tt2 in your editor and enter the following:

    [% META title = 'Create/Update Book' %]
    
    [%# Render the HTML::FormFu Form %]
    [% form %]
    
    <p><a href="[% Catalyst.uri_for('list') %]">Return to book list</a></p>

Add Links for Create and Update via `HTML::FormFu`

Open root/src/books/list.tt2 in your editor and add the following to the bottom of the existing file:

    <p>
      HTML::FormFu:
      <a href="[% Catalyst.uri_for('formfu_create') %]">Create</a>
    </p>

This adds a new link to the bottom of the book list page that we can use to easily launch our HTML::FormFu-based form.

Test The <HTML::FormFu> Create Form

Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

Login as test01 (password: mypass). Once at the Book List page, click the new HTML::FormFu "Create" link at the bottom to display the form. Fill in the following values: Title = "Internetworking with TCP/IP Vol. II", Rating = "4", and Author = "Comer". Click Submit, and you will be returned to the Book List page with a "Book created" status message displayed.

Also note that this implementation allows you to can create books with bogus information. Although we have constrained the authors with the drop-down list (note that this isn't bulletproof because we still have not prevented a user from "hacking" the form to specify other values), there are no restrictions on items such as the length of the title (for example, you can create a one-letter title) and value for the rating (you can use any number you want, and even non-numeric values with SQLite). The next section will address this concern.

Note: Depending on the database you are using and how you established the columns in your tables, the database could obviously provide various levels of "type enforcement" on your data. The key point being made in the previous paragraph is that the web application itself is not performing any validation.

`HTML::FormFu` VALIDATION AND FILTERING

Although the use of HTML::FormFu in the previous section did provide an automated mechanism to build the form, the real power of this module stems from functionality that can automatically validate and filter the user input. Validation uses constraints to be sure that users input appropriate data (for example, that the email field of a form contains a valid email address). Filtering can also be used to remove extraneous whitespace from fields or to escape meta-characters in user input.

Add Constraints

Open root/forms/books/formfu_create.yml in your editor and update it to match:

    ---
    # indicator is the field that is used to test for form submission
    indicator: submit
    # Start listing the form elements
    elements:
        # The first element will be a text field for the title
        - type: Text
          name: title
          label: Title
          # This is an optional 'mouse over' title pop-up
          attributes:
            title: Enter a book title here
          # Use Filter to clean up the input data
          filter:
            # Remove whitespace at both ends
            - TrimEdges
            # Escape HTML characters for safety
            - HTMLEscape
          # Add constraints for the field
          constraints:
            # The user cannot leave this field blank
            - SingleValue
            # Force the length to be between 5 and 40 chars
            - type: Length
              min: 5
              max: 40
              # Override the default of 'Invalid input'
              message: Length must be between 5 and 40 characters
    
        # Another text field for the numeric rating
        - type: Text
          name: rating
          label: Rating
          attributes:
            title: Enter a rating between 1 and 5 here
          # Use Filter to clean up the input data
          filter:
            # Remove whitespace at both ends
            - TrimEdges
            # Remove everything except digits
            - NonNumeric
          # Add constraints to the field
          constraints:
            - SingleValue
            # Make sure it's a number
            - Integer
    
        # Add a select list for the author selection.  Note that we will
        # dynamically fill in all the authors from the controller but we
        # could manually set items in the select by adding this YAML code:
        # options:
        #   - [ '1', 'Bastien' ]
        #   - [ '2', 'Nasseh'  ]
        - type: Select
          name: authors
          label: Author
          # Convert the drop-down to a multi-select list
          multiple: 1
          # Display 3 entries (user can scroll to see others)
          size: 3
          # One could argue we don't need to do filters or constraints for
          # a select list, but it's smart to do validation and sanity
          # checks on this data in case a user "hacks" the input
          # Use Filter to clean up the input data
          filter:
            # Remove whitespace at both ends
            - TrimEdges
            # Escape HTML characters for safety
            - HTMLEscape
          # Add constraints to the field
          constraints:
            # Make sure it's a number
            - Integer
    
        # The submit button
        - type: Submit
          name: submit
          value: Submit
    
    # Globally ensure that each field only specified one value
    constraints:
        # The user cannot leave any fields blank
        - Required

NOTE: Copying and pasting YAML from perl documentation is sometimes tricky. See the "Copy-Paste versions of the YAML Config" section of this document for a foolproof procedure.

The main changes are:

The Select element for authors is changed from a single-select drop-down to a multi-select list by adding configuration for the multiple and size options in formfu_create.yml.
Constraints are added to provide validation of the user input. See HTML::FormFu::Constraint for other constraints that are available.
A variety of filters are run on every field to remove and escape unwanted input. See HTML::FormFu::Filter for more filter options.

Try Out the Updated Form

Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

Make sure you are still logged in as test01 and try adding a book with various errors: title less than 5 characters, non-numeric rating, a rating of 0 or 6, etc. Also try selecting one, two, and zero authors. When you click Submit, the HTML::FormFu constraint items will validate the logic and insert feedback as appropriate. Try adding blank spaces at the front or the back of the title and note that it will be removed.

CREATE AND UPDATE/EDIT ACTION

Let's expand the work done above to add an edit action. First, open lib/MyApp/Controller/Books.pm and add the following method to the bottom:

    =head2 formfu_edit
    
    Use HTML::FormFu to update an existing book
    
    =cut
    
    sub formfu_edit :Local :FormConfig('books/formfu_create.yml') {
        my ($self, $c, $id) = @_;
    
        # Get the specified book
        my $book = $c->model('DB::Books')->find($id);
    
        # Make sure we were able to get a book
        unless ($book) {
            $c->flash->{error_msg} = "Invalid book -- Cannot edit";
            $c->response->redirect($c->uri_for('list'));
            $c->detach;
        }
    
        # Get the form that the :FormConfig attribute saved in the stash
        my $form = $c->stash->{form};
    
        # Check if the form as been submitted (vs. displaying the initial
        # form) and if the data based validation.  "submitted_and_valid"
        # is shorthand for "$form->submitted && !$form->has_errors"
        if ($form->submitted_and_valid) {
            # Save the form data for the book
            $form->save_to_model($book);
            # Set a status message for the user
            $c->flash->{status_msg} = 'Book edited';
            # Return to the books list
            $c->response->redirect($c->uri_for('list'));
            $c->detach;
        } else {
            # Get the authors from the DB
            my @authorObjs = $c->model("DB::Authors")->all();
            # Create an array of arrayrefs where each arrayref is an author
            my @authors;
            foreach (sort {$a->last_name cmp $b->last_name} @authorObjs) {
                push(@authors, [$_->id, $_->last_name]);
            }
            # Get the select added by the config file
            my $select = $form->get_element({type => 'Select'});
            # Add the authors to it
            $select->options(\@authors);
            # Populate the form with existing values from DB
            $form->defaults_from_model($book);
        }
    
        # Set the template
        $c->stash->{template} = 'books/formfu_create.tt2';
    }

Most of this code should look familiar to what we used in the formfu_create method (in fact, we should probably centralize some of the common code in separate methods). The main differences are:

We accept $id as an argument via the URL.
We use $id to look up the existing book from the database.
We make sure the $id and book lookup returned a valid book. If not, we set the error message and return to the book list.
If the form has been submitted and passes validation, we skip creating a new book and just use $form->save_to_model to update the existing book.
If the form is being displayed for the first time (or has failed validation and it being redisplayed), we use $form->default_from_model to populate the form with data from the database.

Then, edit root/src/books/list.tt2 and add a new link below the existing "Delete" link that allows us to edit/update each existing book. The last <td> cell in the book list table should look like the following:

    <td>
      [% # Add a link to delete a book %]
      <a href="[% Catalyst.uri_for('delete', book.id) %]">Delete</a>
      [% # Add a link to edit a book %]
      <a href="[% Catalyst.uri_for('formfu_edit', book.id) %]">Edit</a>
    </td>

Try Out the Edit/Update Feature

Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

Make sure you are still logged in as test01 and go to the http://localhost:3000/books/list URL in your browser. Click the "Edit" link next to "Internetworking with TCP/IP Vol. II", change the rating to a 3, the "II" at end of the title to the number "2", add Stevens as a co-author (control-click), and click Submit. You will then be returned to the book list with a "Book edited" message at the top in green. Experiment with other edits to various books.

Copy-Paste versions of the YAML Config.

YAML, the config format used in formfu depends on whitespace and can behave strangely in perl documentation because POD is also whitespace dependent. If you copy and paste the YAML below into the file root/forms/books/formfu_create.yml and then run the following perl oneliner, you're pretty much guaranteed to get valid YAML:

 $ perl -p -i -e 's/\s+\|//g' root/forms/books/formfu_create.yml

YAML for the first half of the tutorial:

    |---
    |# indicator is the field that is used to test for form submission
    |indicator: submit
    |# Start listing the form elements
    |elements:
    |    # The first element will be a text field for the title
    |    - type: Text
    |      name: title
    |      label: Title
    |      # This is an optional 'mouse over' title pop-up
    |      attributes:
    |        title: Enter a book title here
    |
    |    # Another text field for the numeric rating
    |    - type: Text
    |      name: rating
    |      label: Rating
    |      attributes:
    |        title: Enter a rating between 1 and 5 here
    |
    |    # Add a drop-down list for the author selection.  Note that we will
    |    # dynamically fill in all the authors from the controller but we
    |    # could manually set items in the drop-list by adding this YAML code:
    |    # options:
    |    #   - [ '1', 'Bastien' ]
    |    #   - [ '2', 'Nasseh'  ]
    |    - type: Select
    |      name: authors
    |      label: Author
    |
    |    # The submit button
    |    - type: Submit
    |      name: submit
    |      value: Submit

YAML for the second part of the tutorial

    |---
    |# indicator is the field that is used to test for form submission
    |indicator: submit
    |# Start listing the form elements
    |elements:
    |    # The first element will be a text field for the title
    |    - type: Text
    |      name: title
    |      label: Title
    |      # This is an optional 'mouse over' title pop-up
    |      attributes:
    |        title: Enter a book title here
    |      # Use Filter to clean up the input data
    |      filter:
    |        # Remove whitespace at both ends
    |        - TrimEdges
    |        # Escape HTML characters for safety
    |        - HTMLEscape
    |      # Add constraints for the field
    |      constraints:
    |        # The user cannot leave this field blank
    |        - SingleValue
    |        # Force the length to be between 5 and 40 chars
    |        - type: Length
    |          min: 5
    |          max: 40
    |          # Override the default of 'Invalid input'
    |          message: Length must be between 5 and 40 characters
    |
    |    # Another text field for the numeric rating
    |    - type: Text
    |      name: rating
    |      label: Rating
    |      attributes:
    |        title: Enter a rating between 1 and 5 here
    |      # Use Filter to clean up the input data
    |      filter:
    |        # Remove whitespace at both ends
    |        - TrimEdges
    |        # Remove everything except digits
    |        - NonNumeric
    |      # Add constraints to the field
    |      constraints:
    |        - SingleValue
    |        # Make sure it's a number
    |        - Integer
    |
    |    # Add a select list for the author selection.  Note that we will
    |    # dynamically fill in all the authors from the controller but we
    |    # could manually set items in the select by adding this YAML code:
    |    # options:
    |    #   - [ '1', 'Bastien' ]
    |    #   - [ '2', 'Nasseh'  ]
    |    - type: Select
    |      name: authors
    |      label: Author
    |      # Convert the drop-down to a multi-select list
    |      multiple: 1
    |      # Display 3 entries (user can scroll to see others)
    |      size: 3
    |      # One could argue we don't need to do filters or constraints for
    |      # a select list, but it's smart to do validation and sanity
    |      # checks on this data in case a user "hacks" the input
    |      # Use Filter to clean up the input data
    |      filter:
    |        # Remove whitespace at both ends
    |        - TrimEdges
    |        # Escape HTML characters for safety
    |        - HTMLEscape
    |      # Add constraints to the field
    |      constraints:
    |        # Make sure it's a number
    |        - Integer
    |
    |    # The submit button
    |    - type: Submit
    |      name: submit
    |      value: Submit
    |
    |# Globally ensure that each field only specified one value
    |constraints:
    |    # The user cannot leave any fields blank
    |    - Required

AUTHOR

Kennedy Clark, hkclark@gmail.com

Please report any errors, issues or suggestions to the author. The most recent version of the Catalyst Tutorial can be found at http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/.

To install Catalyst::Manual, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Catalyst::Manual

CPAN shell

perl -MCPAN -e shell
install Catalyst::Manual

For more information on module installation, please visit the detailed CPAN module installation guide.

	Global
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`g` `a`	Go to author
`g` `c`	Go to changes
`g` `i`	Go to issues
`g` `d`	Go to dist
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NAME

OVERVIEW

DESCRIPTION

Install HTML::FormFu

HTML::FormFu FORM CREATION

Inherit From Catalyst::Controller::HTML::FormFu

Add Action to Display and Save the Form

Create a Form Config File

Update the CSS

Create a Template Page To Display The Form

Add Links for Create and Update via HTML::FormFu

Test The <HTML::FormFu> Create Form

HTML::FormFu VALIDATION AND FILTERING

Add Constraints

Try Out the Updated Form

CREATE AND UPDATE/EDIT ACTION

Try Out the Edit/Update Feature

Copy-Paste versions of the YAML Config.

YAML for the first half of the tutorial:

YAML for the second part of the tutorial

AUTHOR

Module Install Instructions

Install `HTML::FormFu`

`HTML::FormFu` FORM CREATION

Inherit From `Catalyst::Controller::HTML::FormFu`

Add Links for Create and Update via `HTML::FormFu`

`HTML::FormFu` VALIDATION AND FILTERING